How to check if a string is empty

Short answer

Compare the string with an empty string using the strict operator:

<?php
 
$name = '';
 
var_dump($name === '');

Output:

bool(true)

A string of spaces

A user may type nothing but spaces. Remove them with trim() before the check:

<?php
 
$name = '   ';
 
var_dump(trim($name) === '');

Output:

bool(true)

Why not empty()

empty() treats the string '0' as empty too. If zero is a valid answer, that check gets it wrong:

<?php
 
$quantity = '0';
 
var_dump(empty($quantity));
var_dump($quantity === '');

Output:

bool(true)
bool(false)